Staggered laser-etch line graphic system, method and articles of manufacture

ABSTRACT

A staggered laser-etch line graphic system, method, and articles of manufacture are provided. One described method includes the steps of laser engraving a first plurality of lines associated with a first component section of a graphic on a surface of an article; laser engraving a second plurality of lines associated with a second component section of the graphic on the surface of the article; and controlling said laser engraving of the first plurality of lines and said laser engraving of second plurality of lines to reduce the visual impact of a demarcation line separating the first component section of the graphic and the second component section of the graphic.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY

This patent application claims the benefit of U.S. ProvisionalApplication No. 61/172,893, entitled “Staggered Laser-Etch Line GraphicSystem, Method and Articles of Manufacture,” and filed Apr. 27, 2009,the entirety of which is incorporated herein and to which priority isclaimed.

FIELD OF THE INVENTION

The present invention relates to laser engraving graphics onto articlesurfaces, and more particularly to a staggered laser-etch line graphicsystem, method, and articles of manufacture.

BACKGROUND OF THE INVENTION

Manufactured articles can present large or substantial viewable surfaceareas. Often it is desirable to apply a graphic design to one or more ofthese surface areas. Graphic designs include ordered patterns, randomnon-patterns, discrete simple graphic elements, complex graphical imagesand the like. Printing, painting, and engraving are just a few examplesof techniques that may be employed to apply a graphic design to anarticle. Engraving may involve carving, cutting, or etching the surfaceof the assembly components to permanently remove surface area materialof the article. Laser etching is particularly useful for creatinggraphic designs on the surface of an article. The graphic design may beetched into the article surface during its manufacture. A design may beapplied after an article has been incorporated as a component to anotherarticle or structure. Common articles having substantial surface areasfor applying a graphic design are boards, doors, facings, floors,moldings, siding, fencing, railing, and walls.

One of the difficulties associated with the laser etching of a graphicdesign over a substantial surface area is that laser etching equipmentis typically not capable of etching a large detailed graphic design in asingle unitary application of the whole graphic over the surface on anarticle. This difficulty is particularly acute when the articles ofmanufacture are mass-produced in a repeating process or a continuousprocess such as an extrusion process. This can occur in the context of amanufacturing assembly line process involving the continuous repeatedapplications of a detailed graphic design in real-time. This can be ahigh-speed process as occurs with articles having a flat surface. Or aslower process involving the application of a complex graphic design toa flat, curved or three-dimensional surface of an article, such as in anindexing process of manufacture performed on a continuous or batchbasis. To some extent the difficulties in applying a detailed or complexlaser etched graphic design can also occur in craft-based methods ofmanufacturing.

To address this need, computerized laser etching methods have beendeveloped for laser marking a graphic design in smaller sub-componentsections of a multi-component assembly of the whole graphic design. Thegraphic design is first partitioned into a plurality of graphic designcomponent sections. Each of the graphic design sections is assigned to acorresponding component section of the surface area divided into aplurality of components for presenting the whole graphic design. Thegraphic design sections are laser marked onto corresponding componentsections of an article's surface area. The graphic image may be nolarger than the field size of the laser, however.

A problem can arise in the context of joining the component sectionsduring the laser etching process to form a unitary image of a wholegraphic design, particularly for relatively large work pieces that havea visible area exceeding the field size of the laser. The location atwhich the component sections of the graphic are joined is called theborder or demarcation line, wherein the laser etched lines from separatecomponent sections of the whole graphic meet together. Often thismeeting point will involve a slight gap or a slight overlap in the lasergraphic lines associated with separate but adjoining component sectionalareas. This problem typically arises in the application of joinedgraphic designs as the meeting point will involve a visually perceptibleimperfection forming a notable demarcation line between the twocomponent sections of the graphic design when applied by laser etching.The demarcation is a substantial problem as it detracts from the overallaesthetic quality of the manufactured article.

BRIEF SUMMARY OF THE INVENTION

A first aspect of the invention provides a method for reducing a visualimpact of a demarcation line of a graphic, the method comprising laserengraving a first plurality of lines associated with a first componentsection of a graphic on a surface of an article; laser engraving asecond plurality of lines associated with a second component section ofthe graphic on the surface of the article; and controlling said firstplurality of lines and said second plurality of lines to reduce thevisual impact of a demarcation line separating the first componentsection of the graphic and the second component section of the graphic.

Another aspect of the invention provides a method for laser engraving agraphic on an article, the method comprising laser engraving a graphicon a surface of an article, the graphic comprised of a first pluralityof lines and a second plurality of lines adjoined in a curvilinearsection.

Another aspect of the invention provides a method of making an articleof manufacture with a laser etched graphic applied on a surface of thearticle in at least two component sections, sharing at least one border,and forming a unitary image of the graphic on the surface of thearticle, wherein such unitary image is greater than the field size of alaser and where the method involves using multiple lasers to etch theindividual sections such that the complete graphic is lazed on the partwhich is larger than the field size of the laser.

Another aspect of the invention provides an article of manufacturehaving a laser etched graphic, said article comprising a first pluralityof laser engraved lines associated with a first component section of agraphic; a second plurality of laser engraved lines associated with asecond component section sharing a border with said first componentsection of said graphic; wherein the first plurality of lines and thesecond plurality of lines are controlled to reduce the visual impact ofa demarcation line separating the first component section and the secondcomponent section.

Another aspect of the invention provides a system for laser engraving agraphic on a surface of an article, comprising a laser engravingapparatus for laser engraving a surface of an article, and a visualimpact controller in communication with the laser engraving apparatusand configured to reduce the visual impact of a demarcation lineseparating a first plurality of laser engraved lines and a secondplurality of laser engraving lines by controlling the laser engraving ofthe first plurality of laser engraving lines and the second plurality oflaser engraving lines.

Another aspect of the invention provides a method for laser engraving agraphic on an article, the method comprising providing a laser having adefined native field size; formatting a graphic having at least onedimension exceeding the defined native field size into a plurality ofportions which collectively define a unity graphic image; providing asurface having a dimension exceeding the native field size; and laserengraving the plurality of portions onto the surface to reproduce theunitary graphic image onto the surface.

Other aspects of the invention, including apparatus, systems, methods,and the like which constitute part of the invention, will become moreapparent upon reading the following detailed description of theexemplary embodiments and viewing the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings and color photos are incorporated in andconstitute part of the specification. The drawings, together with thegeneral description given above and the detailed description of theexemplary embodiments and methods given below, serve to explain theprinciples of the invention. In such drawings:

FIG. 1 is a flowchart of a method for staggered laser etch linesaccording to an embodiment of the invention;

FIG. 2 is a schematic view of a system for staggered laser etch linesaccording to another embodiment of the invention;

FIG. 3A is a schematic view of a system for staggered laser etch linesaccording to another embodiment of the invention;

FIG. 3B is a schematic view of a system for scribing staggered laseretch lines in a continuous “print-on-the-fly” process according toanother embodiment of the invention;

FIG. 3C is a schematic view of a system for staggered laser etch lineswhere multiple lasers are utilized to create the graphic according toanother embodiment of the invention;

FIG. 3D is a schematic view of a system for staggered laser etch lineswhere the laser scan head is moved according to another embodiment ofthe invention;

FIG. 3E is a schematic view of a system for surfacing making an articlewith both a laser and a printer according to another embodiment of theinvention;

FIG. 4 is a schematic view of a printing station for staggered laseretch lines according to another embodiment of the invention;

FIG. 5 is a schematic view of a printer applying ink and laser scribingto an article having a channel feature according to another embodimentof the invention;

FIG. 6A is an illustration of non-staggered laser etch lines;

FIG. 6B is an illustration of staggered laser etch lines according toanother embodiment of the invention;

FIG. 6C is an illustration of staggered laser etch lines according toanother embodiment of the invention;

FIG. 7 is a schematic view of a graphic image that is composed of aseries of discontinuous lines, as may be the case for some low densitywood grain images, in which case individual graphic sections that makeup the unitary graphic image may be divided into two parts by anadjoining line that is curvilinear;

FIG. 8 is an illustration of a system for staggered laser etch linesaccording to another embodiment of the invention;

FIG. 9 is an illustration of a system for staggered laser etch linesaccording to another embodiment of the invention;

FIG. 10 is an illustration of a system for staggered laser etch linesaccording to another embodiment of the invention;

FIG. 11 is an illustration of a laser engraved article demonstrating ahigh visual impact of demarcation according to one embodiment of theinvention;

FIG. 12 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 13 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 14 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 15 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 16 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 17 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 18 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 19 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention;

FIG. 20 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention; and

FIG. 21 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Reference will now be made in detail to exemplary embodiments andmethods of the invention as illustrated in the accompanying drawings, inwhich like reference characters designate like or corresponding partsthroughout the drawings. It should be noted, however, that the inventionin its broader aspects is not limited to the specific details,representative devices and methods, and illustrative examples shown anddescribed in this section in connection with the exemplary embodimentsand methods. The invention according to its various aspects isparticularly pointed out and distinctly claimed in the attached claimsread in view of this specification, and appropriate equivalents.

The terms “laser” and “laser beam” may be used interchangeably. Theterms “mark” and “scribe” are used interchangeably herein, and as usedmean to irradiate an article or component, such as a board made ofplastic lumber, with a laser to form a graphic design, such as a woodgrain image. In the course of marking and scribing, the laser causes avisually perceptible change to the article surface, such as by causingremoval, ablation, or etching of surface material or colortransformation of a dye. The result is a visually-perceptible graphic onthe article, made up of laser etch lines forming a design, pattern, etc.

The terms “graphic” and “graphic design” are used interchangeablyherein, and as used herein, refer to decorative and artistic designs,non-decorative designs, patterns, graphic images, wood grain,alpha-numeric characters, corporate and trade logos, or other markings,etc.

The terms “lines per inch” and “LPI” refer to the density of the graphiclaser lines within a single inch perpendicular cross-section length ofthe area to be laser etched. More specifically, this relates to thenumber of graphic laser lines etched within a perpendicularcross-length. These measures are expressed in LPI amounts, such as thehigher density 60 LPI or lower density 40 LPI measures referring,respectively, to a laser etching with 60 or 40 laser-etching lineswithin a perpendicular cross-section having a width of one inch.

The term “border” or “border line”, when used in reference to the borderformed between two graphic component sectional areas, refers to thesection or area formed or left between two component sections of a laserengraved graphic. When a graphic is applied in unmodified componentsections (i.e., without staggering and/or randomizing as describedbelow), than the border may comprise a highly visual straight line. Theborder between component sections may or may not be modified to minimizeany visual imperfections in the application of the graphic design. Anunmodified border in the context of the invention will generally presenta discrete straight line between component sections, which if visuallyperceptible is also a demarcation.

The term “demarcation” “line of demarcation”, or “demarcation line”,when used in reference to the border formed between two graphiccomponent sections, refers to the visually perceptible marking betweenthe component sections in a graphic design when applied in componentsections by laser etching of laser graphic lines without modification tothe laser graphic lines in the component sections to minimize orovercome the perceptibility of the demarcation.

The terms “interlaced” or “staggering”, when used in reference to thestaggering of graphic laser lines at the border between two graphiccomponent sectional areas, refers to the percentage of overlap at theborder of the laser graphic lines from the two separate componentsectional areas. For example, “staggering” means that a graphic laserline from a first component sectional area can extend across thestraight border into the second component sectional area. The term “10%staggering” means the cross-border extension of the laser-etching linemay vary, randomly or otherwise, from 0 to 10% of the component sectionlength, when both the first and second component sectional areas haveequal dimensions of height and length. The staggering is generallyautomated using a computer program or software module.

The terms “randomized sub-unit length” or “randomization of sub-unitlength”, when used in reference to graphic laser lines forming acomponent sectional area of a design graphic, means the randomizedbreaking-up or partitioning of the graphic laser etch lines torandomized sub-unit lengths. These sub-unit lengths are permutations ofother depending on the number of sub-units into which the whole graphicline is partitioned, and the degree of variability in sub-unit lengthselected in the designated degree of randomization chosen. Therandomization is generally automated using a random number generator orthe like within a computer program or software module.

The terms “staggered” or “staggering”, when used in reference to graphiclaser-etched lines forming a component sectional area of a designgraphic, refers to the use of the techniques of staggering,randomization or a combination of both these techniques in the laseretching of graphic lines in the component sections in order to minimize,overcome or remove the perceptibility of visual imperfections in thecomponent sections of design graphic, such as a demarcation line betweencomponent sections. The staggering is generally automated using acomputer program or software module.

The term “article” or “manufactured article” as used herein includes butis not limited to building components. Building components include, forexample and not necessarily limitation, flooring, decking, wall panels,door panels, door trim, siding, cabinetry, railings, moldings, etc. Forexplanatory purposes, exemplary embodiments below are described inrelation to building components. It should be understood that themethods and systems described herein and the following exemplaryembodiments may be used for marking/scribing components other thanbuilding components such as plastic components, textile fabrics, leatherand vinyl articles, etc.

The articles of manufacture according to the invention are not limitedas to the materials from which they are made. Exemplary materials thatmay be laser-etched or otherwise marked or treated using the systems andmethods embodied herein include plastic lumber, glass (tempered glassand/or annealed glass), stone, ceramic, granite, leather, wood,engineered wood, laminates, metal, specialty polymers, gypsum,fiberglass reinforced plastic, wood composites, vinyl, acrylic,polyvinylchloride, hardboard, veneer, low profile carpet tiles, fabrics,paper, etc.

U.S. Pat. No. 6,692,815 entitled “Extruded Plastic Lumber and Method ofManufacture” discloses conventional plastic lumber made withhigh-density polyethylene or polypropylene, combined with wood flour andother fillers, and the methods of making the plastic lumber. Anotherplastic lumber material is disclosed in U.S. Pat. No. 5,539,027,entitled “Advanced Polymer/Wood Composite Structural Member” disclosinganother polymer-wood composite that may make up the article for laseretching or other marking. This is a PVC plastic lumber compositecontaining, for example, 30 to 50 wt % of sawdust along with 50 to 70 wt% of a polyvinylchloride (PVC) polymer.

Laser etching is the practice of using lasers to etch, mark or decoratean object. The technique can be complex and a computer system isdesirable to drive the movements of the laser beam. Despite thiscomplexity, very precise and clean engravings can be achieved at a highrate. The technique does not involve tool bits which contact theengraving surface and wear out. This is considered an advantage overalternative engraving technologies where bit heads have to be replacedregularly. A laser etching machine can be thought of as three mainparts: a laser, a controller, and a surface. The laser is like apencil—the beam emitted from it allows the controller to trace lines orpatterns onto the surface. The beam may either remove material from thesubstrate upon which it impinges or it may transform a dye that coatsthe surface or is intermixed into the substrate. The result is either aremoval of material or a color transformation or both, with the resultthat the graphic is applied to the surface. The controller is usually acomputer and controls the direction, intensity, speed of movement, andspread of the laser beam aimed at the surface. The surface is picked tomatch what the laser can act on.

There are three general types of laser etching machines. In an X-Ytable, usually, the workpiece surface is stationary and the laser orlaser scan head moves around in X and Y directions drawing raster bitsor vector lines. In a second general type, the laser is stationary andthe workpiece moves. Sometimes the workpiece moves in the Y axis and thelaser in the X axis. A third type of type of laser etching machine isfor three-dimensional workpieces where the laser traverses athree-dimensional surface, such as in an indexed manufacturingoperation, and laser pulsing produces the desired image, generally on araster or vector basis. In this third type of machine, both the laserand workpiece are stationary and galvanometer (galvo) mirrors move thelaser beam over the workpiece surface. Laser etching machines accordingto these general types are available commercially from LasX Industries,Inc.

The point where the laser touches the surface is typically the focalplane of the laser's optical system, and is usually synonymous with itsfocal point. This point is typically small, perhaps less than a fractionof a millimeter, and dependent upon the optics and field size of thelaser. The area inside this focal point and often immediatelysurrounding this focal point (referred to as the heat affected zone) issignificantly affected when the laser beam passes over the surface. Theenergy delivered by the laser changes the surface of the material underthe focal point. It may heat up the surface and subsequently vaporizethe material, or perhaps the material may fracture (known as “glass” or“glass up”) and flake off the surface. This is how material is removedfrom the surface to create an etching. If the surface material isvaporized during laser etching, ventilation through the use of blowersor a vacuum pump are often used to remove the noxious fumes and smokearising from the process and for removal of debris on the surface toallow the laser to continue etching. A laser can remove material veryefficiently because the laser beam can be designed to deliver energy tothe surface in a manner which converts a high percentage of the lightenergy into heat. The beam is highly focused and collimated—in mostnon-reflective materials like wood, plastics and enamel surfaces, theconversion of light energy to heat is substantial. However, theequipment used in laser engraving may heat up rather quickly. Coolingsystems are often used with the laser. Alternatively, the laser beam maybe pulsed to decrease the amount of excessive heating. The laser scanspeed determines throughput of the process or the rate at which thesubstrates such as building components are lazed with the desiredgraphic.

Different patterns can be etched by programming the controller totraverse a particular path for the laser beam over time. The trace ofthe laser beam is carefully regulated to achieve a desired removal depthof material. For example, crisscrossed paths are generally avoided toensure that each etched surface is exposed to the laser only once, andso the same amount of material is removed. The speed at which the beammoves across the material is also considered in creating etchingpatterns. Changing the intensity and spread of the beam allows moreflexibility in the design. For example, by changing the proportion oftime (known as “duty-cycle”) the laser is turned on during each pulse,the power delivered to the etching surface can be controlledappropriately for the material. Changing the power on the fly or theduty cycle on the fly allows for the creation of unique designs wherethe intensity of the graphic can change along each laser etched line aswell as along individual sections of the graphic.

FIG. 1 is a flowchart of a method for staggered laser etch linesaccording to an embodiment of the invention. Articles that may besubject to marking according to the present invention include syntheticbuilding components intended to replicate natural wood. Especiallycontemplated are exterior entry doors and interior passage doors, decksand deck components, siding, paneling, furniture components, etc.,whether of solid construction or so-called hollow core doors constructedfrom a peripheral door frame with opposite door skins. Peripheral doorframes include stiles and rails which define the sides and top andbottom of the door. A pair of door skins have interior surfaces securedto opposite sides of the peripheral door frame via bonding, mechanicalfasteners, etc., and opposite exterior surfaces. As known in the art,hollow core doors may include additional support members and/or corematerials (e.g., foam) disposed between the skins.

Other building components that may be subject to the exemplary methodsand systems described herein include furniture and cabinet doors, closetand bifold doors, door trim, window frames, furniture elements,cabinetry, picture frames, tables, molded wall paneling, wainscot,decking, wall panels, siding, railings, window trim, architectural trim,flooring, etc. For explanatory purposes, exemplary embodiments below aredescribed in relation to building components, in particular doorstructures. It should be understood that the methods and systemsdescribed herein may be used for marking other building component andarticles other than building components.

The exemplary embodiments and methods described herein are particularlyintended for use with engineered composite materials such as mediumdensity fiberboard (MDF) and high density hardboard. Engineeredcomposite materials generally contain cellulosic fibers or otherparticles, often broken down in a defibrator, and a resin and optionallywax, which are compressed at high temperatures and pressures. Thecellulosic fibers/particles often constitute more than 90 weight percentof the material. The cellulosic component typically but not necessarilyis wood fiber. The binding resin is typically a thermoset. An example ofan engineered composite material is disclosed in U.S. Pat. No.5,344,484. Examples of other materials that may be treated using thesystems and methods embodied herein include fiberglass-reinforced sheetmolding compound (SMC) polyesters, paints and basecoats on substrates,polymer sheets, veneers, papers, and natural materials, e.g. wood.

As shown in FIG. 1, the method 100 begins with laser engraving a firstplurality of lines associated with a first component section of agraphic 102. A laser engraved graphic typically consists of multiplelines laser etched on a surface. Together, in aggregate, the pluralityof etched lines can reproduce the overall appearance, or effect, of thegraphic.

Next, the method 100 continues with laser engraving a second pluralityof lines associated with a second component section of a graphic 104. Agraphic may be divided into two or more component sections. For example,in order to etch a graphic greater in at least one dimension than thefield size of a laser, than multiple component sections can be used toetch the graphic on the surface of an article. One or more lasers maylaser engrave the first plurality of lines and/or the second pluralityof lines.

Various techniques may be used to align the multiple component sectionsto provide a high quality image. In one embodiment, after a firstsection of the graphic is laser engraved, a position of the laserengraved first section is indexed, and the second section of the graphicis laser engraved beginning at the indexed position. In anotherembodiment, after a first component section of the graphic is laserengraved, the laser scanning head is moved to a location adjacent to thelaser engraved first component section,

Finally, the method 100 concludes by controlling said laser engraving ofthe first plurality of lines and said laser engraving of secondplurality of lines to reduce the visual impact of a demarcation lineseparating the first component section of the graphic and the secondcomponent section of the graphic 106.

The laser engraving of the first plurality of lines and the laserengraving of the second plurality of lines can be controlled in one or acombination of ways to reduce the visual impact of the demarcation line.In one embodiment, controlling comprises staggering said first pluralityof lines with said second plurality of lines by adjusting the lengths ofsaid first plurality of lines and said second plurality of lines. Bystaggering the first component section and the second component section,the demarcation line can take on a more curvilinear shape, as opposed tothe straight line of a non-staggered application of the graphic. A morecurvilinear demarcation line may reduce the visual impact of thedemarcation line, and thus creating a higher quality product.

Controlling the laser engraving of the first plurality of lines and thelaser engraving of the second plurality of lines can also includerandomizing the laser engraving of at least one of said first pluralityof lines and said second plurality of lines by partitioning said linesinto a random number of random length sub-unit lengths, controlling theline per inch density of said first plurality of lines and said secondplurality of lines, and/or controlling the laser power of the laserengraving of the first plurality of lines and the second plurality oflines.

FIG. 2 is a schematic view of a system for staggered laser etch linesaccording to another embodiment of the invention. As shown in FIG. 2,the system 200 is configured to laser etch graphics onto a surface. Thesystem 200 comprises a controller 202 in communication with the laser204 and gas tank 208.

The laser 204 generates a laser beam 206. The laser beam 206 output fromthe laser 204 may be adjusted from 500 watts up to 2,500 watts or more.The laser beam 206 may be directed and/or manipulated by x-axis mirror218 and/or y-axis minor 220. An x-axis galvanometer 210 is incommunication with x-axis mirror 218, and can rotate x-axis mirror 218in the direction of 214 to direct the laser beam 206 along the x-axis.As the x-axis mirror 218 is rotated, laser beam 206 may be directedalong the x-axis. Similarly, a y-axis galvanometer 212 is incommunication with the y-axis mirror 220, and can rotate y-axis mirror220 to further direct laser beam 206. As the y-axis mirror 220 isrotated, laser beam 206 may be directed along the y-axis. The controller202 can be configured to control the x-axis galvanometer 210 and they-axis galvanometer 212 by manipulating the power provided to eachgalvanometer 210, 212.

After the laser beam 206 is directed by the x-axis minor 218 and they-axis mirror 220, the laser beam 206 travels through a focusing lens222. The focusing lens can be configured to focus the laser beam 206into a directed laser beam 224 onto a surface 230 of a workpiece 228.The focusing lens 222 may be a multi-spot on a flat plane as the laserbeam 206 moves across the workpiece 228 to scribe a graphic. One or moreof the focusing lens 222, x-axis galvanometer 210, y-axis galvanometer212, x-axis minor 218 and/or y-axis mirror 220 can be housed in agalvanometer block (not shown).

The system 200 further comprises a working surface 226. Working surface226 may comprise a solid substrate such as a table, or even a fluidizedbed. One or more workpieces 228 to be laser etched are placed on theworking surface 226. The workpiece 228 includes a surface 230 forlaser-etching and/or printing.

The position of the workpiece 228 and the surface of the workpiece 230may be adjusted in a variety of ways. The working surface 226 may movevertically to adjust the distance from the focusing lens 222 to theworkpiece surface 230. The working surface 226 may comprise a conveyerbelt capable of horizontal movement.

As the x-axis mirror 218 and the y-axis mirror 220 move, or rotate, thefocused laser beam 224 is directed across the surface 230 of theworkpiece. In some embodiments, the focused laser beam 224 hits thesurface 230 of the workpiece 228 at a perpendicular, i.e. 90° angle.Variations in the laser-markings on the surface 230 may be achieved byadjusting the angle of incidence of the focused laser beam 224 on thesurface 230, such as between angles of about 45° to about 135°.

As the focused laser beam 224 contacts and moves about the surface 230of the workpiece, a graphic 232 is laser-etched onto the surface 230.The movements and timing of the mirrors 218, 220 and the power of thelaser beam 206 can be controlled by the control computer 202 tolaser-etch a specific graphic 232. As referred to herein, relativemovement may involve movement of the focused laser beam 224 (e.g., usingthe mirror system) as the workpiece 228 remains stationary, movement ofthe workpiece 228 while the directed laser beam 224 remains stationary,or a combination of simultaneous movement of the laser beam 224 and theworkpiece 228 in different directions and/or at different speeds.

The control computer 202 and/or a second computer (not shown in FIG. 2)may be used to form a desired graphic. For example, a graphic can bescanned into a second computer, converted into the proper format, andthen communicated to the control computer 202. The control computer thencontrols the galvanometers 210, 212, mirrors 218, 220, and the poweroutput of the laser 206 to form the graphic 232 on the surface 230 ofthe workpiece 228.

The system 200 can also include a tank 208 to inject a gas such as aninert gas into the working zone. The amount of gas can be controlled bythe numerical control computer or by other means. The power and speedsshould be controlled to effect the desired color change while avoidingundesirably consequences of over-treatment, such as completecarbonization, burn-through and/or melting of the workpiece 228.

Computer hardware and software for carrying out the embodiments of theinvention described herein may be any kind, e.g., either generalpurpose, or some specific purpose such as a workstation. The computermay be a Pentium® or higher class computer, running an operating systemsuch as Windows XP®, Windows Vista®, or Linux®, or may be a Macintosh®computer. The computer may also be a portable or mobile computer, suchas a PDA, cell phone, or laptop. The programs may be written in sourcecode, C, C plus, Java or any other programming language. The programsmay be resident on a storage medium, e.g., magnetic or optical, of,e.g., the computer hard drive, a removable disk or media such as amemory stick or SD media, or other removable medium. The programs mayalso be run over a network, for example, with a server or other machinesending signals to one or more local machines, which allows the localmachine(s) to carry out the operations described herein.

In the course of marking and scribing, the laser beam 224 applies heatto the plastic composite working surface of the substrate, therebycausing a visually perceptible change to the substrate surface, such asby causing removal, ablation, or etching of a coating of the substrate,removal, ablation or etching of substrate material, transformation of adye such as by dye removal or alteration of the color of the dye, etc.The result is a visually-perceptible graphic marking on or in thesubstrate. The term graphic refers to decorative and artistic designs,non-decorative designs, patterns, graphic images, simulated wood grain,alpha-numeric characters, logos, other markings, etc. It should beunderstood that the methods and systems described herein may be used formarking/scribing materials other than plastic lumber or other buildingmaterials.

It should be understood that the present invention may be carried outusing various other laser systems having alternative layouts andcomponents to those shown in FIGS. 1 and 2, or as otherwise generallydescribed above. The laser scanning system configuration can bepre-objective architecture where the laser beam is reflected from twoscan mirrors and then directed through a focusing lens. Alternately, thelaser scanning system architecture can be post-objective where the laserbeam is first passed through the focusing lens and then reflected fromthe scan mirrors onto the work piece. Any number of optics and lensescan be introduced into either architecture. Examples of other such lasersystems are disclosed in U.S. Patent Application Publication No.2007/0108170, to Costin et al.

Other embodiments of the invention combine ink-jet printing with laserscribing. In certain exemplary embodiments of the invention a method isprovided for marking the surface of an article in which a first graphicdesign element is laser scribed into the article surface, and a secondgraphic design element is printed on the surface of the article. Thefirst and second graphic design elements are applied to the articlesurface in registry with one another so that the overall graphic designis a cooperative interaction between the lased and printed elements.Spatially, registering the first and second graphic elements may involvetheir superimposition or juxtaposition on the article surface using, forexample, predetermined coordinates. Aesthetically, the lased and printedgraphic design elements produce a synergistic effect that in exemplaryembodiments is manifested as a high quality simulation of naturalmaterials that could not be attained by either laser marking or printingwithout the other. In certain exemplary embodiments the first and secondgraphic design elements may also produce a textural contrast asdiscussed below. Laser scribing and printing may be conducted in anyorder or simultaneously, although preferably the substrate is lazedfirst and ink-jet printed second.

FIG. 3A is a schematic view of a system for staggered laser etch linesaccording to another embodiment of the invention. Articles according tothe invention may be marked using a high-speed high power laser system300 such as shown in FIG. 3A. The laser 304 may be a high power laser,such as a CO₂ laser of at least 500 watts and up to 2500 watts or more.The output 306 of the laser 304 is coupled to a laser scanning head 308.The laser scanning head 308 includes a relatively light weight coatedmirror that is capable receiving the output 306 generated by the laser304 and generating a directed laser beam 324 at a relatively high speed.The directed laser output 324 can be scanned across the work piece 330on working surface 326. The workpiece 330 may comprise a plastic lumberbuilding component or some other material.

As shown in FIG. 3A, the system 300 a includes a controller 302. Thecontroller 302 may store control information for controlling the laserbefore, during, and/or after the laser engraving process. The controlinformation may be linked to one or many different graphics, such as awood grain pattern, or a floral pattern 332. The controller 302 iscapable of keeping up with the high scan speeds of the laser scanninghead 308 produced by the lightweight mirrors and able to make thenecessary power changes at the specified speed. To create fineresolution graphics, the controller 302 can make such power changes athigh rates, such as 10,000 to 50,000 power changes per second. The type(e.g., complexity and intricacy) and depth of the graphic will alsoinfluence how it is scribed on the substrate.

FIG. 3B is a schematic view of a system for scribing staggered laseretch lines in a continuous “print-on-the-fly” process according toanother embodiment of the invention. As shown in FIG. 3B, the system 300b comprises a conveyer apparatus 338. The conveyer apparatus 338 canmove, or convey the work piece 330 under the directed laser 324. Thespeed of the conveyor apparatus 338 may be fixed, or predetermined. Or,the controller 302 may continuously set and maintain the proper speed ofthe conveyer apparatus to assure accurate registration of the componentsections that collectively comprise the graphic being applied. In oneembodiment, the conveyor apparatus 338 is a roller based table where theworkpiece is pulled along the conveyor by means of a nip roll system.

FIG. 3C is a schematic view of a system for staggered laser etch lineswhere multiple lasers are utilized to create the graphic according toanother embodiment of the invention. As shown in FIG. 3C, the system 300c comprises a plurality of lasers 304 a, 304 b. One or more lasercontrollers 302 (not shown in FIG. 3C) may control the plurality oflasers 304 a, 304 b. A plurality of laser scanning heads 308 a, 308 bare in communication with the plurality of lasers 304 a, 304 b, andlaser engrave graphics onto the article 330 by generating directed laserbeams 324 a, 324 b. While each laser 304 a, 304 b may have its owncontroller, a single master controller may control all lasers 304 a, 304b, or control individual controllers. By using multiple lasers, eachlaser 304 a, 304 b may apply a component section, or portion, of thegraphic. In order to assure a unitary, uniform composite image, eachcomponent section may be in registration.

FIG. 3D is a schematic view of a system for staggered laser etch lineswhere the laser scan head is moved according to another embodiment ofthe invention. As shown in FIG. 3D, the system 300 d comprises laserscanning head 308 operably connected to a first track 340 a and a secondtrack 340 b. The laser scanning head 308 can move along the tracks 340a, 340 b so that the work piece 330 may remain stationary on the supportapparatus 326. The laser scanning head 308 may be carried on a rail,track, robot arm or similar system to allow the laser scan head 308 tomove along the work piece 330 as it applies the graphic in portions ontothe work piece. A plurality of component sections of the graphic appliedby the laser scanning head 308 may be in registration to assure aunitary and uniform graphic applied to the work piece.

It should be understood that the present invention may be carried outusing various other laser systems having alternative layouts andcomponents to those shown in FIGS. 2 and 3A-3E, or as otherwisegenerally described above. It should be understood that methods of thepresent invention may be carried out using various other laser systems,such as the laser system disclosed in U.S. Patent ApplicationPublication No. 2007/0108170, to Costin et al.

Other embodiments of the invention may combine ink-jet printing withlaser scribing. In certain exemplary embodiments of the invention amethod is provided for marking the surface of an article in which afirst graphic design element is laser scribed into the article surface,and a second graphic design element is printed on the surface of thearticle. The first and second graphic design elements are applied to thearticle surface in registry with one another so that the overall graphicdesign is a cooperative interaction between the lased and printedelements. Spatially, registering the first and second graphic elementsmay involve their superimposition or juxtaposition on the articlesurface using, for example, predetermined coordinates. Aesthetically,the lased and printed graphic design elements produce a synergisticeffect that in exemplary embodiments is manifested as a high qualitysimulation of natural materials that could not be attained by eitherlaser marking or printing without the other. In certain exemplaryembodiments the first and second graphic design elements may alsoproduce a textural contrast as discussed below. Laser scribing andprinting may be conducted in any order or simultaneously, althoughpreferably the substrate first is lazed and then ink jet printed.

A system for laser scribing and ink printing graphic design on articlessuch as building components using a high-speed high power laser and inkjet printer is shown in FIGS. 3E, 4, and 5. It should be understood thatthe elements of the system described below are exemplary and are notnecessarily intended to be limiting on the scope of the invention. Othersystems and apparatus may be substituted for those described below, andthe system and apparatus described below may be modified as dictated bythe nature of the graphic pattern and the article.

FIG. 3E is a schematic view of a system for surfacing making an articlewith both a laser and a printer according to another embodiment of theinvention. As shown in FIG. 3E, a system 300 e comprises a work stationcomputer 350. The work station computer 350 may be accessed by anoperator, and receive input specifying one or more parameters related toa graphic to be laser engraved on an article. For example, a user mayspecify a specific graphic to be laser engraved on the surface of thearticle, along with a speed and a quality level. The work stationcomputer 350 is in operative communication with the controller 302 and aprinter controller 352. The controller 302 is in communication with thelaser 304 and the laser scanning head 308 to direct the output of thelaser 306. The printer controller 352 communicates with an ink-jetprinting apparatus 354.

FIG. 4 is a schematic view of a printing station for staggered laseretch lines according to another embodiment of the invention. As shown inFIG. 4, the system 400 comprises a printing station 402. The printingstation 402 includes an ink-jet printer 404 with at least one ink jetprint head 406. The ink-jet print head 406 is mounted for horizontalmovement in the direction of arrow 408, which is perpendicular to thedirection of movement of the article 430 on the working surface 426,indicated by arrow 410. The ink jet print head 406 may move in thedirection 408 across the entire width of the door structure 430. Theprinter 402 may be a flat bed printer, such as available through IncaDigital Printers Limited of Cambridge, United Kingdom.

FIG. 5 is a schematic view of a printer applying ink and laser scribingto an article having a channel feature according to another embodimentof the invention. As shown in FIG. 5, a printer 500 is configured toprint on a surface of an article 514. The printer 500 may include a rail502 for supporting the print head 504. The rail 502 provides for lateralmovement of the print head 504 under the control of the print controller506. The print head 504 is shown with a UV curing lamp 508 for dryingand curing the ink jet ink. Alternatively, a separate curing station(not shown) may be provided. Ink jet ink droplets 510 are emitted fromone or more nozzles 512 of the print head 504.

It should be understood that the printer 500 may include multiple printheads 506 arranged in rows or arrays, so that each pass may effectiveprint in more than one set of print grid positions. The nozzles 510 mayemit droplets 510 of various desired colors in order to create a desiredcolor. While the printing apparatus 500 described above is an ink jetprinter, it should be understood that other printer types, such as laserprinters, may be used.

An object of the invention is to reduce or eliminate the visual impact,i.e. visual perceptibility, of a demarcation line at the border betweentwo adjoining component sections of a graphic which is laser engravedonto the surface of an article. This object is accomplished bycontrolling the laser engraving of the adjoining component sections,such as by staggering and/or randomizing the laser engraved linesassociated with the two component sections. Staggering occurs at theborder between the two component sections. Randomization of laser etchedline sub-length occurs within each individual laser etched line in acomponent section within which it occurs. The concept can incorporateboth staggering and the randomizing of the sub-lengths of the laser etchlines from one or both component sections with those from an adjoiningcomponent section.

FIGS. 6A, 6B, and 6C provide a simplified representation of the conceptsof randomizing and staggering according to the invention. FIGS. 6A, 6B,and 6C all illustrate a graphic made by laser-engraving a substrate oran article surface. In each of FIGS. 6A, 6B, and 6C, two componentsections are shown, with a first component section 602 a, 602 b, 602 cand a second component section 604 a, 604 b, 604 c. Each componentsection of the FIGS. 6A-6C share a border represented by lines E. Ineach component section there are four laser engraved lines from top tobottom. Each first component section comprises laser engraved linesL601, L602, L603 and L604. Each second component section comprises laserengraved lines L611, L612, L613, and L614. Each laser engraved line hasan endpoint, E, where a laser engraved line from either componentsections meets the corresponding laser engraved line of the othercomponent section at the border.

FIG. 6A is an illustration of non-staggered laser etch lines accordingto an embodiment of the invention. As shown in FIG. 6A, a graphiccomprises a first component section 602 a and a second component section604 a. The first component section 602 a comprises a first plurality oflaser engraved lines L601A-L604 a. The second component section 604 acomprises a second plurality of laser engraved lines L611 a-L614 a.Neither the lengths of the first plurality of lines L601 a-604 a or thelengths of the second plurality of lines L611 a-L614 a have beenadjusted. Accordingly, the endpoints E of each laser engraved line up ina straight demarcation line, or border.

Conventional methods of laser engraving a graphic 600 a do not staggerlaser engraved lines, and result in a highly perceptible demarcationline, i.e. a demarcation line with a high visual impact. Consumersexamining articles produced by laser engraving graphics with nostaggering may immediately spot the line of demarcation, even from adistance, due to its high visual impact.

FIG. 6B is an illustration of staggered laser etch lines according toanother embodiment of the invention. As shown in FIG. 6B, the graphic600 b comprises a first component section 602 b and a second componentsection 604 b. The first plurality of lines L601 b-L604 b and the secondplurality of lines L611 b-L614 b are staggered, as illustrated by theshifting border lines E. The staggering shown in FIG. 6B may represent alow amount of staggering, i.e. adjusting the lengths of each of theplurality of laser engraved lines up to 10%.

At the low staggering illustrated in FIG. 6B, the individual laserengraved lines join at staggered locations, i.e. in a curvilinear line.Because of the staggered lengths and the resulting curvilineardemarcation line, the visual impact of the demarcation line is reducedcompared to the visual impact of the demarcation line of a non-staggeredgraphic such as 600 a. The demarcation at the borders between each laserengraved line is less obvious, or perceptible, because the demarcationis dispersed.

FIG. 6C is an illustration of staggered laser etch lines according toanother embodiment of the invention. The graphic 600 c comprises agraphic with a high amount of staggering, i.e. with the lengths of theeach plurality of laser engraved lines adjusted up to 50%. As shown bythe high staggering in FIG. 6C, the demarcation line is spread over alarger area than the low staggering in FIG. 6B, or the non staggering inFIG. 6A. From a distance, the demarcation line of a graphic 600 c withhigh staggering, in effect, disappears, and thus has zero visual impact.

The amount of staggering of the laser engraved lines may vary from zerostaggering up to 50% of the length of the laser engraved lines, such as10%, 12%, 17%, 25%, 40%, 50%, etc. In one embodiment of the invention,the level of staggering among the individual lines varies randomly, orhas no perceivable pattern, between zero staggering and maximumstaggering. A highly randomized amount of staggering may be preferableso that the lengths of the laser engraved lines have a high degree ofvariation, and the resulting demarcation line is highly curvilinear.

In some embodiments of the invention, the degree of staggering of eachlaser line is controlled. The degree of staggering from the bordercenter point can be changed from very little to very large, i.e. from 0%to 50%. The degree of staggering and staggering randomization is setthrough programming controls that automate application of the graphicdesign from a raster or vector file. The major advantage to adding astaggering effect to each component section is to prevent or reduce thevisual perceptibility of any lines of demarcation from areas where thelines from one component section of the graphic meet to anothercomponent section.

The visual impact of the demarcation line may also be controlled throughother methods. For example, control or manipulation of laser power,laser scan speed, laser frequency, process control factors, and linedensity of graphic laser lines per inch (i.e., LPI) may be combined withstaggered to further reduce the visual impact of the demarcation line.Combinations of these methods and factors in applying detailed woodgrain graphic designs has yielded novel and surprising results inremoving or lowering the perceptibility of any demarcation line betweencomponent sections when the wood grain graphic was laser scribed to thesurface of a plastic lumber article.

FIG. 7 is a schematic view of a graphic image that is composed of aseries of discontinuous lines, as may be the case for some low densitywood grain images, in which case individual graphic sections that makeup the unitary graphic image may be divided into two parts by anadjoining line that is curvilinear. As shown in FIG. 7, an articlesurface 700 comprises a first component section of a graphic 702 and asecond component section of a graphic 704 separated by a demarcationline 706.

The first component section of the graphic 702 comprises a firstplurality of laser engraved lines L701, L702, L703, L704, L705, L706,L707 and L708. The second component section of the graphic 704 comprisesa second plurality of laser engraved lines L711, L712, L713, L714, L715,L716, L717 and L718. The line of demarcation 706 represents an area(i.e. a border) between the first component section 702 and the secondcomponent section 704. As shown in FIG. 7, the line of demarcation is acurvilinear section, or line.

As shown in FIG. 7, the first plurality of laser engraved lines L701-708are staggered with the second plurality of laser engraved linesL711-L718, as the lengths of the first plurality of laser engraved linesL701-L708 and the lengths of the second plurality of laser engravedlines L711-L718 have been adjusted.

FIG. 8 is an illustration of a system for staggered laser etch linesaccording to another embodiment of the invention. As shown in FIG. 8,the system 800 may comprise a nip roll system. The system 800 comprisesa laser engraver 802 and a work station computer 804. Articles are fedinto the system 800 via an input conveyer 806, and leave the system viaan output conveyer 808.

FIG. 9 is an illustration of a system for staggered laser etch linesaccording to another embodiment of the invention. As shown in FIG. 9,the system 900 includes a controller 902. The controller 902 is incommunication with a laser (not shown in FIG. 9), and can control theprocess of laser engraving a graphic onto a surface of an article.

In one example, a wood grain pattern graphic 6 inches wide and 16 feetlong is supplied in a digital format (i.e. a digital file) and importedinto laser etch control program executed by the controller. Next, thecontroller formats the wood grain pattern graphic into a plurality ofcomponent sections to be laser engraved onto the surface of a piece ofplastic lumber. A 12 foot long piece of plastic lumber may be dividedinto 24 six inch parts, in order to maximize throughput within a 20 inchfield. Once the number of component sections is determined, thecontroller divides the wood grain pattern graphic into the calculatednumber of component sections. The resulting file may be saved as a job,and process parameters, such as laser speed, lines per inch, and laserpower, are selected. Finally, the laser system is activated, andarticles are fed into the system via a conveyer belt. The laser engravesthe wood grain pattern graphic onto the surface of a moving article viaa continuous “print-on-fly” process.

The grain of the wood grain pattern graphic flows along the length ofthe wood composite plastic lumber and therefore is generally laseretched in the same direction. The speed of the conveyer system can beadjusted depending upon the graphic and the speed of the laser beam.From a manufacturing and economical perspective, it may be preferred toimmediately begin lazing the next article after the completion of theprevious article.

As shown in FIG. 10, a shuttle system may be used to reduce or eliminateany slight wobble or movement of the articles as they move through thesystem during continuously lazing. In this way, more accurate graphicscan be engraved onto the surface of the article. One alternative methodfor preventing wobble, or movement of the article, comprises a frame1002. The frame 1002 may be positioned along the input conveyor andextend through the work enclosure to the output conveyor. Articles to belaser engraved may be held in place by being positioned inside theframe, which also serves to constrain side-to-side movement of thearticle while it progresses through the system.

Various tests were conducted in order to determine the influence of anumber of variables on the degree of perceptibility of the demarcation.These variables included the laser power, the lines per inch of thegraphic, the speed of the laser beam and thus the conveyor speed, theboundary settings in graphics application software, and the percentstaggering selected in the graphics application software. The parametersand results are summarized in Table I and described below.

TABLE I Nip Roll Laser Trial Parameters FIG. Laser Power LPI (linesLaser Scan Speed Web # Randomization (watts) per inch) (meters persecond) fpm Results 11 0% 2000 60 10 2.5 Distinct Demarcation Lines 1210% 1000 60 10 2.5 Demarcation Lines Still Visible 13 20% 2000 60 10 0Demarcation Lines Obvious 14 20% 2000 60 10 2.5 Demarcation LinesObvious 15 10% 1000 60 10 2.5 Demarcation Lines Obvious 16 10% 2000 6010 2.5 Demarcation Lines Somewhat Masked 17 10% 1000 40 10 2.5Demarcation Lines Lighter 18 50% 2000 60 10 2.5 Invisible DemarcationLines 19 50% 1000 60 10 2.5 Good (Low) Visibility of Demarcation Lines20 50% 2375 60 15 5.5 Good (Low) Visibility of Demarcation Lines

FIG. 11 is an illustration of a laser engraved article demonstrating ahigh visual impact of demarcation according to one embodiment of theinvention. As shown in FIG. 11, an initial laser scribing test run wasperformed without staggering or other randomization as a basis forcomparison. The first set of data on laser etching wood grain patternson a plastic lumber wood composite article produced poor results in thata clear line of demarcation could be seen at the intersection of eachcomponent section of the graphic. Every six inches along the length ofthe plastic lumber, a strong demarcation line 1102 was visuallyperceptible as shown in FIG. 11.

FIG. 12 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention. As shown in FIG. 12, another run was prepared with the laseretched lines in the component sections of the wood grain graphicinterlaced 10% produced unexpected and surprisingly improved resultswhich showed demarcation lines 1202 a, 1202 b, 1202 c with reducedvisual impact as shown in FIG. 12.

FIGS. 13 and 14 are illustrations laser engraved articles demonstratingvisual impact of demarcation according to embodiments of the invention.FIG. 13 illustrates a laser scribing test run with a moving laser and astationary article, i.e. stationary lazing. FIG. 14 illustrates a laserscribing test run with a moving article. As shown in FIGS. 13-14, thedemarcation line 1302 and demarcation line 1402 were still slightlyperceptible when the laser etching was done on both the stationaryarticle 1300 and the moving articles 1400. Because the demarcation line1302 was still evident in the in the stationary product of FIG. 13,persisting demarcation may not be associated with the moving process orany associated side-to-side wobble of the plastic lumber as it movesthrough the laser scribing system. Therefore joining two laser etchedsections either by moving the laser or by moving the part or by movingboth generate this defect.

The effect of the laser power was tested. FIGS. 15 and 16 areillustrations laser engraved articles demonstrating visual impact ofdemarcation according to embodiments of the invention. FIG. 15 shows anarticle 1500 lazed at 1,000 watts power. FIG. 16 shows an article 1600lazed at 2,000 watts power with all other parameters equal to article1500, as indicated in Table I. Comparison of these two samples 1500 and1600 indicates, surprisingly and unexpectedly, that the higher powertends to mask the degree of demarcation somewhat, but the demarcationwas still evident at close examination.

FIG. 17 is an illustration of a laser engraved article demonstratingvisual impact of demarcation according to one embodiment of theinvention. The effect of lines per inch (LPI) etch line density wastested. Lines per inch represent how many laser lines per inch were usedto laser etch the graphic. As shown in FIGS. 15 and 17, in the article1700, the lower line per inch setting of 40 LPI tends to results inlighter lines of demarcation 1702 at the intersection of the componentsections compared to demarcation lines 1502 of the article 1500, asshown in FIG. 15, where the same graphic was lazed at 60 LPI.

The effect of different boundary settings in the graphic software wastested. The purpose of the boundary is to prevent the laser fromsuddenly turning on at the beginning of the laser line and suddenlyturning off at the end of the laser line, allowing the laser to overexcite. Boundary settings activate the laser at a specified distanceprior to the beginning of the laser line and deactivate the laser at aspecified distance at the end of the laser line. The controller canexecute graphics application software which can receive selections of aboundary length and a boundary power. Boundary power should be set lowenough to where it is not visible. Several variations on the boundarysetting were examined in which the maximum and minimum settings for bothboundary length and boundary power were tested. Changing these settingshad little impact on the quality of the applied graphic and did notprevent any lines of demarcation.

The effect of control factor settings was tested. Control factorsettings can be used to maintain consistency between where the laser isdirected to engrave a line and where the laser actually engraves theline. When the laser is directed to begin engraving a line, there istypically a delay. Selecting an optimum control factor setting willenhance precision, and ensure the laser actually engraves at the exact,directed location. A less than optimum control factor setting couldresult in the laser engraving before or after the exact directed point,resulting in an undesirable graphic. Control factor trials at theextreme settings identified the optimum control factor setting. Althoughthe optimum control factor settings improved the quality of the graphic,the optimum settings did not eliminate visible of demarcation linesbetween graphic component sections.

The effect of staggering, or interlace, percentage was tested. Thispercentage relates to how far an etching line from one sectionalcomponent of graphic can extend into another. Several trials wereconducted changing the new interlace setting in graphics applicationsoftware from 10% to 50%. FIG. 15 illustrates an article 1500 with aKnotty Pine graphic image laser engraved at 10% staggering. FIG. 18illustrates an article 1800 with the same Knotty Pine graphic imagelaser engraved at 50% staggering. Increasing the staggering, orinterlace setting to 50% appears to completely eliminate the visualimpact, or visibility, of demarcation lines. FIG. 19 shows severalseparate plastic lumber articles 1900 lazed at 50% interlace with a Teakwood grain graphic pattern. There are no discernable lines ofdemarcation evident in this case. The actual intersection of the partslazed appears to be well masked.

The effect of conveyor speed was tested. The conveyor speed measured infeet per minute is a function of the scan speed of the laser beam(measured in meters per second). FIGS. 20 and 21 show the impact ofincreasing the laser scan speed from 10 to 15 meters per second with acorresponding increase in conveyor line speed from 2.5 feet per minuteto 5.5 feet per minute. Doubling the line speed does not change thevisual impact of the demarcation lines on article 2000 or article 2100so long as the interlace is set at 50%. This result is particularlysurprising given the unexpected increase in productivity this can allow.

Staggering and randomization work exceptionally well in reducing thevisual impact, or masking, demarcation lines separating componentsections of a graphic. With the wood grain graphic images tested, thedemarcation lines appear to be sufficiently or completely maskedresulting in the lazed product appearing surprisingly realistic andquite attractive, appearing like natural wood grains on plastic lumber.These results suggest a potential breakthrough in the industry.

The foregoing detailed description of the certain exemplary embodimentsof the invention has been provided for the purpose of explaining theprinciples of the invention and its practical application, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with various modifications as are suited to theparticular use contemplated. This description is not intended to beexhaustive or to limit the invention to the precise embodimentsdisclosed. Although only a few embodiments have been disclosed in detailabove, other embodiments are possible and the inventors intend these tobe encompassed within this specification and the scope of the appendedclaims. The specification describes specific examples to accomplish amore general goal that may be accomplished in another way. Modificationsand equivalents will be apparent to practitioners skilled in this artand are encompassed within the spirit and scope of the appended claimsand their appropriate equivalents. This disclosure is intended to beexemplary, and the claims are intended to cover any modification oralternative which might be predictable to a person having ordinary skillin the art. For example, other kinds and wattages of lasers, beyondthose described above, could be used with this technique.

1-18. (canceled)
 19. An article of manufacture having a laser etchedgraphic, said article comprising: a first plurality of laser engravedlines associated with a first component section of a graphic; a secondplurality of laser engraved lines associated with a second componentsection sharing a border with said first component section of saidgraphic; wherein the first plurality of lines and the second pluralityof lines are controlled to reduce the visual impact of a demarcationline separating the first component section and the second componentsection.
 20. A system for laser engraving a graphic on a surface of anarticle, comprising: a laser engraving apparatus for laser engraving agraphic into a surface of an article, and a visual impact controller incommunication with the laser engraving apparatus and configured toseparate the graphic into at least first and second component sectionssharing a border, and further configured to control the laser engravingapparatus by adjusting the lengths of a first plurality of linesassociated with the first component section and a second plurality oflines associated with the second component section to stagger the firstplurality of lines with the second plurality of lines across the border.21. The system according to claim 20, wherein the visual impactcontroller is configured to adjust the lengths of the first plurality oflines and the second plurality of lines up to 10%.
 22. The systemaccording to claim 20, wherein the visual impact controller isconfigured to adjust the lengths of the first plurality of lines and thesecond plurality of lines up to 50%.
 23. The system according to claim20, wherein the visual impact controller is configured to randomize thelengths of the first and second plurality of lines.
 24. The systemaccording to claim 20, wherein the visual impact controller isconfigured to adjust the line per inch density of the first and secondplurality of lines.
 25. The system according to claim 20, wherein thevisual impact controller is configured to control laser power.
 26. Thesystem according to claim 20, wherein the graphic is greater in at leastone dimension than the field size of a laser engraving the firstplurality of lines and the second plurality of lines.
 27. The systemaccording to claim 20, wherein the visual impact controller isconfigured to control the laser engraving apparatus to operate in acontinuous print-on-the fly laser etching process wherein the article iscontinuously moving and a laser beam etches the graphic on the movingarticle.
 28. The system according to claim 20, wherein the visual impactcontroller is configured to index the position of the laser engravedfirst component section of the graphic prior to laser engraving of thesecond component section of the graphic.
 29. A system for laserengraving a graphic on a surface of an article, comprising: a laserengraving apparatus for laser engraving a graphic on a surface of anarticle, and a visual impact controller in communication with the laserengraving apparatus and configured to separate the graphic into at leasta first component section comprising a plurality of first lines havingfirst endpoints and a second component section comprising a plurality ofsecond lines having second endpoints that meet the first endpoints atmeeting points staggered on opposite sides of a border between the firstand second component sections.
 30. A system according to claim 29,wherein the laser engraving apparatus has a defined native field sizethat is less than at least one dimension of the graphic.
 31. A systemaccording to claim 29, wherein the visual impact controller isconfigured to cause the laser engraving apparatus to engrave the firstcomponent section before the second component section.
 32. A systemaccording to claim 29, wherein the visual impact controller isconfigured to cause the laser engraving apparatus to reduce the densityof the first lines and second lines adjacent the first and secondendpoints.
 33. A system according to claim 29, wherein the graphiccomprises a wood grain pattern.
 34. A system for laser engraving agraphic on a surface of an article, comprising: a laser engravingapparatus for laser engraving a graphic on a surface of an article, anda visual impact controller in communication with the laser engravingapparatus and configured to separate the graphic into at least a firstcomponent section comprising a plurality of first lines having staggeredfirst endpoints and a second component section comprising a plurality ofsecond lines having staggered second endpoints that are spaced from thefirst endpoints.
 35. A system according to claim 34, wherein the laserengraving apparatus has a defined native field size that is less than atleast one dimension of the graphic.
 36. A system according to claim 34,wherein the visual impact controller is configured to cause the laserengraving apparatus to engrave the first component section before thesecond component section.
 37. A system according to claim 34, whereinthe visual impact controller is configured to cause the laser engravingapparatus to reduce the density of the first lines and second linesadjacent the first and second endpoints.
 38. A system according to claim34, wherein the graphic comprises a wood grain pattern.